Repair acrylic glass: That's possible

Acrylic glass is one of the most popular plastics. The mostly transparent plastic can be processed excellently and is extremely resistant. Nevertheless, there are also in acrylic glass again and again damage that can be repaired well. We show how it's done.

For repairing techniques suitable for acrylic glass

The technical term for acrylic glass is polymethyl methacrylate, PMMA for short. This makes it one of the thermoplastics (plastomers) and naturally also has their properties. This results in the following options for repairing acrylic glass:

  • Welding (plastic welding and gluing)
  • Heating and molding or forming
  • temper
  • fill with liquid acrylic

Acrylic glass welding

Acrylic glass can be welded differently: by thermal action (heat) and chemically. In the case of thermal welding, it is best for DIY enthusiasts to use a hot-air blower if it is equipped with a suitable nozzle.

The nozzle itself is strongly tapered forward so that it can be heated precisely. Next to the nozzle is a device to hold a plastic rod, which is melted at this heat point. The challenge lies in the exact heating of the acrylic. In addition, it is urgently advisable to temper the finished workpiece subsequently to avoid stress cracks.

Welding by chemical reaction (liquid acrylic or glue)

You can treat the acrylic with a suitable adhesive or dissolve acrylic glass in a suitable dilution (for example, nitro dilution). You can pour the resulting liquid acrylic glass or just use it for welding.

For welding, proceed as with a suitable adhesive: simply coat the acrylic parts to be welded or glued with the solution or the adhesive and press together. The larger the surface thus glued or welded, the more the risk of stress cracks increases.

Repair of a crack or scratch

If acrylic glass is not to be repaired as in the previous examples, or if the defective area is replaced by a complete piece of acrylic glass, you can also prepare a scratch or crack and then fill with liquid acrylic. To do this, proceed as follows: Scratches and cracks first need to be milled in the acrylic glass.

Milling cracks, filling, filling and tempering

Small scratches are bent (u-shaped) and large cracks are milled in a v-shape. Then you fill the liquid acrylic in several steps (with a hypodermic syringe, a silicone syringe, etc.) with acrylic. Make each layer a maximum of 3 to 4 mm thick and let it harden before filling the next layer.

Then in the last layer fill up so much that the padded is a little bit too much and forms an outwardly arched bow. Now you can grind the acrylic glass after curing.

Tips & Tricks

To avoid grinding too deeply into an acrylic glass body, shade the surface with a marker that sticks to the acrylic. This way, you always recognize how much you have already ground and where there is even more need for sanding.

Explicitly with acrylic components with a high safety risk (components of aircraft, view hatches, etc.) you can optimally repair cracks by filling. However, the part must be tempered again when filling with liquid acrylic.

Video Board: HOW TO: glue acrylic (welding)